1. Field of the Invention
The present invention relates to a liquid crystal dispensing apparatus, and more particularly, to a liquid crystal dispensing apparatus for preventing scatter of the liquid crystal resulting from damage to the nozzle from which the liquid crystal is discharged and dropped from the liquid crystal dispensing apparatus. In addition, the present invention relates to a liquid crystal dispensing apparatus for preventing the liquid crystal from being lumped around the nozzle.
2. Description of the Related Art
Recently, various portable electric devices such as mobile phones, personal digital assistants (PDA), and notebook computers have been developed, and therefore, needs for a flat panel display device used in small, light weight, and power-efficient devices for such portable devices are correspondingly increasing. To meet the needs, the flat panel display device such as a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), a and vacuum fluorescent display (VFD) have been actively researched. Of these flat panel display devices, the LCD is highlighted due to current mass production, efficient driving schemes, and superior image quality.
The LCD is a device for displaying information on a screen using refractive anisotropy of liquid crystal. As shown in FIG. 1, the LCD 1 comprises a lower substrate 5, an upper substrate 3, and a liquid crystal layer 7 formed between the lower substrate 5 and the upper substrate 3. The lower substrate 5 is a driving device array substrate. A plurality of pixels (not shown) are formed on the lower substrate 5, and a driving device such as a thin film transistor (TFT) is formed on the each pixel. The upper substrate 3 is a color filter substrate, and a color filter layer for reproducing real color is formed thereon. Further, a pixel electrode and a common electrode are formed on the lower substrate 5 and the upper substrate 3 respectively. An alignment layer is formed on the lower substrate 5 and the upper substrate 3 to align liquid crystal molecules of the liquid crystal layer 7 uniformly.
The lower substrate 5 and the upper substrate 3 are attached by a sealing material 9, and the liquid crystal layer 7 is formed therebetween. In addition, the liquid crystal molecules are reoriented by the driving device formed on the lower substrate 5 to control the amount of light transmitted through the liquid crystal layer, thereby displaying information.
Fabrication processes for a LCD device can be divided into a driving device array substrate process for forming the driving device on the lower substrate 5, a color filter substrate process for forming the color filter on the upper substrate 3, and a cell process. These processes will be described with reference to FIG. 2 as follows.
At first, a plurality of gate lines and data lines are arranged on the lower substrate to define a pixel area by the driving device array process and the thin film transistor connected to the both gate line and the data line is formed on the each pixel area (S101). Also, a pixel electrode, which is connected to the thin film transistor to drive the liquid crystal layer according to a signal applied through the thin film transistor, is formed by the driving device array process.
At the same time, R (Red), G (Green), and B (Blue) color filter layers for reproducing the color and a common electrode are formed on the upper substrate 3 by the color filter process (S104).
In addition, the alignment layer is formed on the lower substrate 5 and the upper substrate 3 respectively, and then the alignment layer is rubbed in order to induce an surface anchoring (that is, a pretilt angle and alignment direction) to the liquid crystal molecules of the liquid crystal layer between the lower substrate 5 and the upper substrate 3 (S102 and S105). Thereafter, a spacer for maintaining the cell gap constant and uniform is dispersed on the lower substrate 5. Then, the sealing material is applied on an outer portion of the upper substrate 3 to attach the lower substrate 5 to the upper substrate 3 by compression (S103, S106, and S107).
On the other hand, the lower substrate 5 and the upper substrate 3 are made from a glass substrate of larger area. That is, the large glass substrate includes a plurality of unit panel areas in which the driving device such as TFT and the color filter layer are formed on. To fabricate the individual liquid crystal unit panel, the assembled glass substrate should be cut into unit panels (S108). Thereafter, the liquid crystal is injected into the empty individual liquid crystal unit panel through a liquid crystal injection opening (S109). The liquid crystal unit panel filled with the liquid crystal is completed by sealing the liquid crystal injection opening, and each liquid crystal unit panel is inspected (S110).
As described above, liquid crystal is injected through the liquid crystal injection opening. At that time, the injection of the liquid crystal is induced by pressure difference. FIG. 3 shows a device for injecting the liquid crystal into the liquid crystal panel. As shown in FIG. 3, a container 12 in which the liquid crystal is contained is placed in a vacuum chamber 10, and the liquid crystal panel is located on an upper portion of the container 12. The vacuum chamber 10 is connected to a vacuum pump to maintain a vacuum state. Further, a liquid crystal panel moving device (not shown) is installed in the vacuum chamber 10 to move the liquid crystal panel from the upper part of the container 12 to the surface of the liquid crystal to contact an injection opening 16 of the liquid crystal panel 1 with the liquid crystal 14 (this method is called as liquid crystal dipping injection method).
When the vacuum in the chamber 10 is released by introducing nitrogen gas (N2) into the vacuum chamber 10 so that the injection opening of the liquid crystal panel 1 contacts the liquid crystal, liquid crystal 14 is injected into the panel through the injection opening by the pressure difference between the pressure in the liquid crystal panel and the pressure of the vacuum chamber. After the liquid crystal is entirely filled into the panel 1, the injection opening 16 is sealed by a sealing material to seal the liquid crystal layer (this method is called as vacuum injection method of liquid crystal).
However, there are several problems in the liquid crystal dipping injection method and/or vacuum injection method as follow.
First, time for the liquid crystal injection into the panel 1 is increased. Generally, a gap thickness between the driving device array substrate and the color filter substrate in the liquid crystal panel is very narrow as order of magnitude of micrometers, and therefore, a very small amount of liquid crystal is injected into the liquid crystal panel per unit time. For example, it takes about 8 hours to inject the liquid crystal completely in fabrication process of the 15 inches-liquid crystal panel 15, the liquid crystal fabrication process time is increased due to the liquid crystal injection of long time, thereby reducing fabricating efficiency.
Second, the liquid crystal consumption is increased in the above liquid crystal injection method. A small amount of liquid crystal of the liquid crystal contained in the container 12 is injected into the liquid crystal panel 10. On the other hand, when the liquid crystal is exposed to atmosphere or to a certain gas, the liquid crystal is contaminated by reaction with the gas. Therefore, the remaining liquid crystal should be discarded after the injection when the liquid crystal 14 contained in the container 12 is injected into a plurality of liquid crystal panels 10, thereby increasing the liquid crystal panel fabrication cost.